In the Ancient Greek mythological tradition, Medusa was a gorgon with the power to instantly turn people to stone once they looked upon her directly. She was turned into a gorgon as a result of Athena's jealousy and her anger at Poseidon's seduction of the girl in Athena's temple.
The exact details of Medusa's birth are inconsistent throughout Greek mythology, but most sources claim that Medusa was born an exceedingly pretty girl with beautiful flowing locks of hair. This made Athena jealous. When Poseidon seduced Medusa in the virgin goddess' temple, Athena became enraged and transformed her into a gorgon, causing Medusa's hair to become snakes. Later, the hero Perseus would be tasked with capturing Medusa's head, which he would accomplish with Athena's aid. Her head still turned living creatures that viewed it into stone. Athena flayed Medusa's skin, creating her aegis, an impenetrable armor. Pegasus and Chrysaor sprang out of Medusa's body when Perseus beheaded her.